States in the northeastern region faring the worst
Parts of this article were used in a special edition on the Himalayas, published in February 1-15, 2023, issue of Down To Earth magazine
Whether caused by natural forces or due to human activities, land subsidence, landslides, soil erosion, drying springs and changing river courses have relegated the Himalayan ecology from being pristine to perishing and deforestation and drying up of springs appear to be the major contributors to these natural hazards.
A decline of 902 square kilometres in forest cover was recorded in hill districts of the country as compared to 2019, found the State of Forest Report, 2021. The loss is much more pronounced in the Himalayan states that reported an overall loss of 1,072 sq km of forest cover.
A closer look revealed geographical disparities, with states in the northeastern region faring the worst.
Arunachal Pradesh (16 hill districts) has lost 257 sq km of forest cover with respect to the State of Forest Report 2019, Manipur (nine hill districts) has lost 249 sq km, Nagaland (11 hill districts) has lost 235 sq km abnd Mizoram (eight hill districts) has lost 186 sq km.
Assam (three hill districts) has lost 107 sq km, Meghalaya (seven hill districts) has lost 73 sq km, Tripura (four hill districts) has lost four sq km, Sikkim (four hill districts) has lost an sq km.
On the other hand, Uttarakhand (13 hill districts), Himachal Pradesh (12 hill districts), Jammu & Kashmir (22 hill districts) and Ladakh (two hill districts) have gained two sq km, nine sq km, 29 sq km and 18 sq km, respectively.
“With deforestation of slopes, environmental degradation processes like soil erosion, slope failures, depletion of soil fertility, scarcity of fuelwood and fodder, increased overland flows, reduced groundwater recharge, loss of biological diversity are accelerated,” noted a 1997 paper by Govind Ballabh Pant Institute of Himalayan Environment and Development, Dehradun.
An assessment of forest degradation trends in the Himalayan mountain region from 1972-1974, 1980-1983 and 1999-2001, led by Maharaj Pandit, a senior visiting fellow with the National University of Singapore’s Scholars Programme, estimated that by 2100, only 10 per cent of the Indian Himalayan land area would be covered by dense forests.
Western Himalayas’ dense forest cover will decrease from 61 per cent in 2000 to 16.8 per cent in 2100; and in eastern Himalayas from 76.2 per cent in 2000 to 38.7 per cent in 2100, said the study.
Sikkim is expected to have the least forest cover by 2100 despite its slower rate of deforestation. This may be because 50 per cent of the state’s geographic area lies above timberline where forest growth is not possible, noted the 2006 assessment.
Forests have been an integral part of Himalayan mountain societies. As many as 1,432 persons were relying on each square kilometre of cultivated land in the Indian Himalaya in the 1980s, said a 2007 paper by the International Centre for Integrated Mountain Development (ICIMOD). In the plains, the corresponding figure was 483.
ICIMOD is an intergovernmental learning and knowledge-sharing centre serving the eight regional member countries of the Hindu Kush Himalaya region.
“Such a situation has over the years manifested itself through encroachments on virgin forestlands and degradation of community lands,” noted the paper. Even today, the forests serve as a source of fodder for livestock, firewood and fuel for the village residents to meet their energy needs.
However, “the share of mountain farmers in the overall degradation of Himalayan natural vegetation and biodiversity is minuscule as compared to the gigantic share of the development paradigm in the area,” ICIMOD authors argued.
Unplanned urbanisation, commercial timber extraction, capitalistic development projects, mining and quarrying were identified as the troublesome “forces of modern development.”
While natural causes have triggered degradation in the state over the last three decades, the past five to six years have recorded damage primarily due to development projects, a forest ranger from Uttarakhand told Down To Earth on condition of anonymity.
“Such damages can not be undone through financial relief or even afforestation. One cannot replace a decades-old tree with a sapling or even a five-year-old tree. Younger trees do not prevent soil erosion or conserve water at the same rate as the older ones,” the ranger said.
One such grievous impact of deforestation is soil erosion. In the Himalayan region, the impact of soil erosion can be felt differently in the western and eastern parts.
Due to higher rainfall in the northeastern hills (1,500-11,500 millimetres annually) as compared to the northwestern hills (350-3,000 mm annually), the former is more vulnerable to soil erosion—22.3 per cent of the area as compared to 12.6 per cent of the area respectively, stated an April 2022 paper.
“Causes and consequences of soil erosion in northeastern Himalaya, India”, said the study published in the journal Current Science.
A 2016 case study on Himachal Pradesh, published in the journal Conservation Agriculture, found that changes in topography, vegetation, rainfall and vegetation canopy considerably trigger soil erosion.
Of the state’s total geographical area, 34 per cent falls under the severe erosion class, 16 per cent under the moderate erosion class and 2 per cent each in the very severe and slight erosion classes.
In 2018, a team of scientists created a soil loss map in Uttarakhand. Their findings, published in journal Current Science, showed that nearly half (48.3 per cent) of the state is above the tolerance limit of 11.2 tonnes per hectare per year of soil loss.
The analysis shows that 6.71 per cent of the land faces moderately severe soil loss, 8.84 per cent severe and 32.72 per cent very severe soil loss.
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In the Himalayan region, soil erosion also gives way to river shifting. Today, the Teesta river flows from Darjeeling and Sikkim into Bangladesh to join the Brahmaputra. But two centuries ago, it used to flow into the Mahananda and the Ganga in Bihar.
“In 1787, due to heavy flood and devastating earthquake, Teesta shifted its course to Brahmaputra basin. If such a sudden river capture occurs today, it will sweep away thousands of villages in a gigantic flash flood,” noted the ICIMOD paper.
The other trend changing the Himalayan ecology is the drying of springs. The Indian Himalayan region is home to three million of the five million springs across the country. These are water sources for 50 million people inhabiting the 11 Himalayan states and two Union Territories. And even those are under threat.
“Any change in spring hydrology has clear ramifications on river hydrology, whether in the headwater regions, where springs manifest themselves as sources of rivers or in the lower-reach plains of river systems where they contribute almost invisibly as base flows to river channels,” according to government thinktank Niti Aayog.
In 2018, the think tank warned that half the springs in the region have either dried up or are becoming seasonal due to erratic rainfall, seismic activity and ecological degradation, which are depleting aquifers in the mountains.
The impact is devastating since one-fifth of the Himalayan population is involved in agriculture and 64 per cent of the cultivable land is irrigated by streams.
Of the 592 community development blocks in the Himalayas, 275 face water scarcity, Kireet Kumar, scientist at the Govind Ballabh Pant Institute of Himalayan Environment and Development, told DTE. Springs are controlled by rainfall and extraction patterns of how the land is used.
Uttarakhand is critical, where 78 of the 90 blocks face water scarcity. In Himachal Pradesh, 60-70 per cent of blocks face a similar fate. Arunachal Pradesh fares slightly better because rainfall patterns here are different and there is less dependence on springs.
“Sikkim is largely dependent on springs and it also faces water scarcity. On Kashmir, however, we have little information,” Kumar noted, adding that the institution is in the process of documenting springs in the Union Territory.
The devastation caused by drying springs extends to forests and wildlife as well, the government assessment, “Report of Working Group I Inventory and Revival of Springs in the Himalayas for Water Security”, noted.
“Depletion has meant disturbances in the water security inside forests and national parks and their fringe areas as well. The problem, therefore, transcends the entire spectrum of dependents and dependencies, from rural and urban water to forests and wildlife,” it said.
As per their findings, it is critical to view “springwater depletion as a nationally pertinent problem and begin to address it through preventive and corrective measures.” This phenomenon is also directly associated with desertification.
“Any change in spring hydrology has clear ramifications on river hydrology, whether in the headwater regions, where springs manifest themselves as sources of rivers or in the lower-reach plains of river systems where they contribute almost invisibly as base flows to river channels,” Niti Aayog argued.
Drying up of springs has led to unsustainable groundwater exploitation, which in turn is causing land subsidence.
United States’s scientific agency National Oceanic and Atmospheric Administration, defined this as “sinking of the ground because of underground material movement,” which includes removal of water or oil, mining activities, earthquakes and soil erosion.
Researchers from the Indian Institute of Geomagnetism in Navi Mumbai conducted a study published in the Journal of Geophysical Research in 2020, which found the Himalayas subside and rise with seasonal changes in groundwater levels.
The ecological degradation of the Himalayas is multifaceted and interlinked. “A changed Himalayan landscape caused by human activities and warming means transformed natural ecosystems through biological invasions and reduced native biodiversity,” Pandit said in a 2013 Nature article.
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